AUSTIN — Fort Bliss personnel will start construction Thursday on temporary shelters that will be used to house immigrant families at the post, said A.F. "Tom" Thomas, a Texas civilian aide to the U.S. Secretary of the Army.

Thomas said the shelters will resemble the tents being used to house more than 300 immigrant children at the port of entry in Tornillo.

"They will have to be modified for families," Thomas said. "Obviously families are going to need their privacy, so they will have to be modified. It can't be exactly the way they were in Tornillo."

Fort Bliss in El Paso is one of two Texas military installations that federal officials have selected to serve as the site of temporary housing for thousands of immigrant families and unaccompanied minors apprehended at the border.

Fort Bliss will have about 12,000 beds, and the post's garrison command will handle construction of the facilities, Thomas said.

Federal officials are using military installations to detain parents with their children, after President Donald Trump signed an executive order to end the separation of children from their parents at the border.

The number of family separations at the border increased dramatically as officials started enforcing a new "zero tolerance" immigration policy adopted by the Trump administration. The policy subjects any adult apprehended crossing the border illegally to criminal prosecution.

When an adult was detained after crossing the border with their children, they were placed in federal jails and the children placed in the custody of the Department of Health and Human Services, because legally children cannot be held in jails.

More than 2,000 children have been separated from their parents since the policy was put into place in April.

Defense Secretary Jim Mattis told reporters earlier this month that it is unclear how many total beds would be needed at each military installation.

“We'll provide whatever support the Department of Homeland Security needs in order to house the people that they have under their custody,” Mattis said. “So we'll work that out week by week. The numbers obviously are dynamic, so we'll have to stay flexible in our logistics support for the Department of Homeland Security.”

Army Col. Rob Manning, a Pentagon spokesman, said Monday that in the long-term, the Department of Defense is “looking at additional facilities so we can break up those populations, so we can manage the impact on the installations," according to a report in the MilitaryTimes.

The Department of Health and Human Services initially considered four bases as possible options for hosting temporary shelters: Dyess Air Force Base in Texas and Little Rock Air Force Base in Arkansas were the other two.

Madlin Mekelburg is a reporter with the USA Today Network Austin Bureau; she may be reached at 512-479-6606; mmekelburg@elpasotimes.com; @madlinbmek on Twitter.